Intra-operative imaging for spinal level localisation in lumbar surgery

Preventing Wrong-Level Spine Surgery

IMPORTANCE

Wrong-level spine surgery (WLSS), a medical error in which a surgeon operates at an unintended vertebral level, is considered a "never event." However, it continues to be a problem in spine surgery today despite the implementation of preventive measures such as the Universal Protocol. The consequences of this event are severe for both the afflicted patient and the treating physician and may result not only in physical harm but also in costly medicolegal proceedings.

OBSERVATIONS

While WLSS incidence varies with the patient population and practice setting, large studies generally report rates below 1%. Given the ubiquity of spine surgery, this remains a concerning number. Risk factors for WLSS can be categorized into three domains: patient factors, imaging issues, and technical issues. Awareness of risk factors allows surgeons to plan for difficulties in level localization. Many techniques for preventing WLSS have been developed, including invasive preoperative marking strategies. Intraoperative radiography or fluoroscopy is necessary but not sufficient for WLSS prevention, in that many errors occur after imaging. The evidence for prevention methods remains of low quality, necessitating future prospective comparison studies.

CONCLUSIONS AND RELEVANCE

Consensus has been reached in professional societies: All spine surgeons should implement WLSS prevention protocols. We assess the reported techniques for safer surgery and emphasize one crucial time-out element: the time-out for level localization (TOLL). Addressing WLSS as a problem specific to spine surgery, we show that by using specially tailored prevention strategies, such measures will allow WLSS to become a true never event.

Formal Radiologist Interpretations of Intraoperative Spine Radiographs Have Low Clinical Value

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

To evaluate the clinical relevance, usefulness, and financial implications of intraoperative radiograph interpretation by radiologists in spine surgery.

SUMMARY OF BACKGROUND DATA

Due to rising health care costs, spine surgery is under scrutiny to maximize value-based care. Formal radiographic analysis remains a potential source of unnecessary health care costs, especially for intraoperative radiographs.

MATERIALS AND METHODS

A retrospective cohort analysis was performed on all adult elective spine surgeries at a single institution between July 2020 and July 2021. Demographic and radiographic data were collected, including intraoperative localization and post-instrumentation radiographs. Financial data were obtained through the institution's price estimator. Radiographic characteristics included time from radiographic imaging to completion of radiologist interpretation report, completion of radiologist interpretation report before the conclusion of surgical procedure, clinical relevance, and clinical usefulness. Reports were considered clinically relevant if the spinal level of the procedure was described and clinically useful if completed before the conclusion of the procedure and deemed clinically relevant.

RESULTS

Four hundred eighty-one intraoperative localization and post-instrumentation radiographs from 360 patients revealed a median delay of 128 minutes between imaging and completion of the interpretive report. Only 38.9% of reports were completed before the conclusion of surgery. There were 79.4% deemed clinically relevant and only 33.5% were clinically useful. Localization reports were completed more frequently before the conclusion of surgery (67.2% vs. 34.4%) but with lower clinical relevance (90.1% vs. 98.5%) and clinical usefulness (60.3% vs. 33.6%) than post-instrumentation reports. Each patient was charged $32 to $34 for the interpretation fee, cumulating a minimum total cost of $15,392.

CONCLUSIONS

Formal radiographic interpretation of intraoperative spine radiographs was of low clinical utility for spine surgeons. Institutions should consider optimizing radiology workflows to improve timeliness and clinical relevance or evaluate the necessity of reflexive consultation to radiology for intraoperative imaging interpretation to ensure that value-based care is maximized during spine surgeries.

LEVEL OF EVIDENCE

3.

Surface landmarks for anterior lumbar access: is fluoroscopy necessary?

BACKGROUND CONTEXT

Anterior lumbar fusion surgery is increasing by an estimated 24% annually in the United States. There is a paucity of precise anatomic guidelines to help surgeons determine the appropriate anterior access incision site.

PURPOSE

The purpose of this study is to compare the available anterior surface landmarks for the L4/L5 and L5/S1 disk levels to the disk levels determined by fluoroscopy, with the goal of creating a guide for surgical incision sites in anterior lumbar access surgery.

STUDY DESIGN

A prospective, observational cohort study of consecutive patients undergoing anterior lumbar spinal exposure for anterior lumbar interbody fusion (ALIF), total disk replacement (TDR), or a combination of the two procedures at levels L4/L5 and/or L5/S1.

PATIENT SAMPLE

All patients (n=183) undergoing primary ALIF and/or TDR surgery from June 2018 to April 2021 at the study sites were assessed for inclusion, and 18 patients were excluded. The remaining 165 patients were included in the study, and a total of 208 surgical levels were exposed.

OUTCOME MEASURES

Mean, standard deviation, and 95% confidence interval (CI) were calculated. At each level, the distance from the symphysis pubis to the target disk level (SD distance) and the distance from the symphysis pubis to the umbilicus (SU distance) were measured, and the SD/SU ratio was calculated. Paired 2-tailed t tests were used to assess significant differences (p<.05). An R² (coefficient of determination) test was used to assess variability of the SD distance, SU distance, and SD/SU ratio at each level.

METHODS

All physiologic and anatomic measures were collected prospectively by the investigators, including intraoperative measurements of SD and SU. Demographic and previous health history data were collected at the time of study enrollment.

RESULTS

The mean age of the 165 study participants was 48±14 years (range 18-80 years), and 97 (61%) were male. A total of 208 disk levels were exposed: 140 at L5/S1 and 68 at L4/L5. For the L5/S1, the SD ranged from 0 to 12.5 cm, with a mean of 5.2±1.9 cm (95% CI 4.88-5.52). For the L4/L5 level, the SD ranged from 6 to 15.5 cm, with a mean of 10.7±2.3 cm (95% CI 10.2-11.2). SD/SU ratios at both levels were lower in overweight (body mass index [BMI] 25-29.9) and obese (BMI 30-34.9) groups than in normal body mass index groups. There was no significant difference in SD/SU ratios between females and males at either L5/S1 (p=.39) or L4/L5 (p=.66).

CONCLUSION

Clinically important variability in SD distances (≥9.5 cm) was observed for both the L5/S1 and L4/L5 disk levels. SD/SU ratios provided more consistent estimates of disk location than SD distance alone, but they still displayed substantial variability. Thus, intraoperative fluoroscopy remains mandatory to accurately plan the surgical incision for anterior lumbar access surgery.

A perspective on wrong level, wrong side, and wrong site spine surgery

Background:

Four of the most common “errors” in spine surgery include: operating on the wrong patient, doing the wrong procedure, performing wrong-level surgery (WLS), and/or performing wrong-sided surgery (WSS). Although preoperative verification protocols (i.e. Universal Protocol, routine Time-Outs, and using the 3 R’s (i.e. right patient, right procedure, right level/side)) have largely limited the first two “errors,” WLS and WSS still occur with an unacceptably high frequency.

Methods:

In 20 studies, we identified the predominant factors contributing to WLS/WSS; unusual/anatomical anomalies/variants (i.e. sacralized lumbar vertebrae. lumbarized sacral vertebra, Klippel-Feil vertebrae, block vertebrae, butterfly vertebrae, obesity/morbid obesity), inadequate/poor interpretation of X-rays/fluoroscopic intraoperative images, and failure to follow different verification protocols.

Results:

“Human error” was another major risk factor contributing to the failure to operate at the correct level/side (WLS/WSS). Factors comprising “human error” included; surgeon/staff fatigue, rushing, emergency circumstances, lack of communication, hierarchical behavior in the operating room, and failure to “speak up”.

Conclusion:

Utilizing the Universal Protocol, routine Time Outs, and the 3 R’s largelly avoid operating on the wrong spine patient, and performing the wrong procedure. However, these guidelines have not yet sufficiently reduced the frequently of WLS and WSS. Greater recognition of the potential pitfalls contributing to WLS/WSS as reviewed in this perspective should better equip spine surgeons to avert/limit such “errors” in the future.